Posterior curve correction using convex posterior hemi-interbody arthrodesis in skeletally immature patients with scoliosis

BACKGROUND CONTEXT: Deformity progression after posterior fusion in skeletally immature patients with scoliosis has remained a topic of debate. It occurs when the anterior segment of the apical zone continues to grow after successful posterior fusion, resulting in progressive bending and rotation of the vertebral bodies. For this reason, circumferential fusion using a combined anterior-posterior approach has been used to prevent this occurrence. PURPOSE: The aim of this study was to report instrumented spinal fusion with convex hemi-interbody arthrodesis using a posterior-only approach in Risser stage 0 or 1 scoliosis patients. STUDY DESIGN: This is a retrospective study. PATIENT SAMPLE: Three patients presenting scoliosis in Risser stage 0 or 1 were enrolled. OUTCOME MEASURES: Postoperative correction rate, bone union, and pulmonary function were examined. METHODS: Premenarchal girls aged 11.3-12.2 years underwent surgical procedure. Follow-up after surgery was on 25, 30, and 36 months. The surgical procedure included soft tissue, costotransverse ligament and facet releases, and Ponte osteotomies. Discectomy followed by intervertebral bone grafting were performed across the periapical zone on the convex side. After placement of segmental pedicle screws, deformity correction was achieved by rod derotation, cantilever reduction, direct vertebral derotation distraction and compression technique. RESULTS: Preoperative thoracic Cobb angle measured 81 degrees (range 64-107), which improved to 23 degrees at final follow-up, resulting in a 72% correction. Solid posterior bony fusion was achieved in all cases at final follow-up. No case showed deterioration of axial rotation at the apex radiographically. Postoperative pulmonary function showed increases in forced vital capacity (preoperation: 1.86 +/- 0.2L; at 2 years: 2.48 +/- 0.1L) and forced expiratory volume in 1 second (preoperation: 1.58 +/- 0.2L; at 2 years: 2.11 +/- 0.1L). CONCLUSIONS: This posterior-only procedure should be considered a suitable option in skeletally immature scoliosis patients where circumferential fusion is indicated and avoiding an anterior thoracotomy is preferable. (C) 2016 Elsevier Inc. All rights reserved.